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From: Jon Kirwan on 21 Dec 2009 15:32 On Mon, 21 Dec 2009 11:18:46 -0800 (PST), Leon <leon355(a)btinternet.com> wrote: >On 20 Dec, 23:40, Jon Kirwan <j...(a)infinitefactors.org> wrote: >> On Sun, 20 Dec 2009 11:19:39 -0800 (PST), Leon >> >> >> >> <leon...(a)btinternet.com> wrote: >> >On 19 Dec, 21:48, Jon Kirwan <j...(a)infinitefactors.org> wrote: >> >> On Sat, 19 Dec 2009 13:31:43 -0800 (PST), -jg >> >> >> <jim.granvi...(a)gmail.com> wrote: >> >> >On Dec 19, 11:00�pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: >> >> >> >> I'm looking at 8127C-AVR-10/09 and on page 28 I find that there is >> >> >> "vcc monitoring" and a VLM circuit. �But for gosh sake that darned >> >> >> thing sucks power -- page 146, curve on the page's bottom. �Cripes. >> >> >> > No such thing as a free lunch ;) >> >> >> Especially true with this part. �I don't recall _ever_ seeing that >> >> high of current requirement (at voltages I can compare across.) �I >> >> think the PIC12's BOR is half that, or less. >> >> >> > Such brownout monitoring is widely varying in uC, and some fudge >> >> >things by sleeping the Monitor on a sub-uA timer. >> >> >> Would that be Microchip's XLP variety? �(I haven't looked, but I >> >> remember reading way-too-good-to-be-true figures for the required >> >> current -- in tens of nanoamp range.) >> >> >They can achieve 20 nA, but the chip isn't actually much use for many >> >applications in that mode. >> >> At what current level do they become useful? >> >> Jon > >They retain the RAM contents at 25 nA, typically, which is some use. >RAM contents are lost at 20 nA. > >They take 500 nA with the RTC and calendar operational. And that's with the BOR operating, I gather. More than acceptable. Now if I can get that in SOT23-6. Jon
From: Leon on 21 Dec 2009 19:22 On 21 Dec, 20:32, Jon Kirwan <j...(a)infinitefactors.org> wrote: > On Mon, 21 Dec 2009 11:18:46 -0800 (PST), Leon > > > > <leon...(a)btinternet.com> wrote: > >On 20 Dec, 23:40, Jon Kirwan <j...(a)infinitefactors.org> wrote: > >> On Sun, 20 Dec 2009 11:19:39 -0800 (PST), Leon > > >> <leon...(a)btinternet.com> wrote: > >> >On 19 Dec, 21:48, Jon Kirwan <j...(a)infinitefactors.org> wrote: > >> >> On Sat, 19 Dec 2009 13:31:43 -0800 (PST), -jg > > >> >> <jim.granvi...(a)gmail.com> wrote: > >> >> >On Dec 19, 11:00 pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: > > >> >> >> I'm looking at 8127C-AVR-10/09 and on page 28 I find that there is > >> >> >> "vcc monitoring" and a VLM circuit. But for gosh sake that darned > >> >> >> thing sucks power -- page 146, curve on the page's bottom. Cripes. > > >> >> > No such thing as a free lunch ;) > > >> >> Especially true with this part. I don't recall _ever_ seeing that > >> >> high of current requirement (at voltages I can compare across.) I > >> >> think the PIC12's BOR is half that, or less. > > >> >> > Such brownout monitoring is widely varying in uC, and some fudge > >> >> >things by sleeping the Monitor on a sub-uA timer. > > >> >> Would that be Microchip's XLP variety? (I haven't looked, but I > >> >> remember reading way-too-good-to-be-true figures for the required > >> >> current -- in tens of nanoamp range.) > > >> >They can achieve 20 nA, but the chip isn't actually much use for many > >> >applications in that mode. > > >> At what current level do they become useful? > > >> Jon > > >They retain the RAM contents at 25 nA, typically, which is some use. > >RAM contents are lost at 20 nA. > > >They take 500 nA with the RTC and calendar operational. > > And that's with the BOR operating, I gather. More than acceptable. > > Now if I can get that in SOT23-6. > > Jon I've got some of the 16-bit XLP chips, but haven't tried them yet. Leon
From: Ulf Samuelsson on 22 Dec 2009 16:23 -jg skrev: > On Dec 19, 11:00 pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: >> I'm looking at 8127C-AVR-10/09 and on page 28 I find that there is >> "vcc monitoring" and a VLM circuit. But for gosh sake that darned >> thing sucks power -- page 146, curve on the page's bottom. Cripes. > > No such thing as a free lunch ;) > > Such brownout monitoring is widely varying in uC, and some fudge > things by sleeping the Monitor on a sub-uA timer. > > One caveat to those contemplating using a Micro as a Watchdog : WHO > is watching your watchdog ? > -jg > When you are in sleep , you do not neccessarily have to have the Brown-Out detector turned on all the time. The Brownout detector is mainly there to block the CPU from executing those instructions that will mess up the chip, like write to EEPROM or Flash. The behaviour of the part during brownout is depending on current draw, If you are in sleep, very little current is going through the device. I am told that the AVR, in sleep mode, will have a RAM retention/ D-Flip-Flop retention voltage of around 0.4V. The Power On Reset of the AVR will trigger around 1.0V so you *have* something watching your watchdog. -- Best Regards Ulf Samuelsson These are my own personal opinions, which may or may not be shared by my employer Atmel Nordic AB
From: Ulf Samuelsson on 22 Dec 2009 16:29 Jon Kirwan skrev: > On Fri, 18 Dec 2009 22:34:46 +0000, Mike Harrison > <mike(a)whitewing.co.uk> wrote: > >> On Thu, 17 Dec 2009 18:35:32 -0800, Jon Kirwan <jonk(a)infinitefactors.org> wrote: >> >>> On Fri, 18 Dec 2009 03:18:37 +0100, Stefan Arentz >>> <stefan(a)keizer.soze.com> wrote: >>> >>>> I'm trying to get my hands on the new 6-pin SOT-23 Tiny controllers >>>> that were recently announced. But I can't find them anywhere. This is >>>> for hobby use so I just want a small bunch of them. >>>> >>>> Has anyone been able to get them at all? I wonder if they have >>>> actually been released. >>> Yo, what!?!? SOT-23-6 8-bit micros?? Where? >> Microchip have had SOT23 MCUs for ages.... PIC10F > > Yeah. Not with brown out. :( > > Jon Brown-Out detectors are really simple analog stuff. You have a trade-off between speed and current. A low current Brownout detector will be sloooow. A slow BOD will not trigger until after you have a chance to start overwriting your EEPROM. If you want something to react below 10 us,then you are going to see 10s of uA. The AVR sleeping BOD combined with the 1.0V power on reset will allow you, in the PicoPower devices, to reach 0,6 uA with system level BOD as well as 32 kHz oscillator running. -- Best Regards Ulf Samuelsson These are my own personal opinions, which may or may not be shared by my employer Atmel Nordic AB
From: -jg on 22 Dec 2009 17:45
On Dec 23, 10:29 am, Ulf Samuelsson <u...(a)a-t-m-e-l.com> wrote: > > The AVR sleeping BOD combined with the 1.0V power on reset > will allow you, in the PicoPower devices, to reach 0,6 uA > with system level BOD as well as 32 kHz oscillator running. However, that's not Tiny4 :) Looking at the SiLabs devices, they claim 50nA for LowBat, but digging deeper shows that's just for a 1V level, and the Vcc monitor is 7uA. Separate Vcc Detectors, are under 1uA Problem with the vanilla 1V 'BOD' trip points, is they hit a black hole in the datasheet, as Clock operation is usually completely unspecified there. Try it on some real devices - can be educational... Still leaves the problem of who is watching your watchdog ? -jg |